The first enclosure-type brick castle in Senieji Trakai was built by Grand Duke Gediminas, who transferred the capital of Lithuania from Kernavė to Trakai (today's Senieji Trakai) before 1321. The wedding of Grand Duke Kęstutis and Birutė was held there and it was the birthplace of the Grand Duke Vytautas in 1350.
The castle in Senieji Trakai was destroyed by the Teutonic Order in 1391, subsequently abandoned and never rebuilt as a new castle had been erected in Trakai by Kęstutis. The ruins of the castle were granted to Benedictian monks by Vytautas in 1405. It is presumed that the present monastery building, dating from the 15th century, holds the remains of Gediminas castle.
Archaeological research on the hillfort mound was carried out in 1996–1997. The findings confirmed the existence of a former rectangular masonry castle wall, which had surrounded the hill. It is supposed that the residential buildings had occupied the area near the church and the churchyard.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.